Despite a great start, the rate of patching OpenSSL servers against the critical Heartbleed vulnerability has slowed down to almost a halt. Around 300,000 servers remain vulnerable and many of them are unlikely to get patched anytime soon.

Over the past month only around 9,000 servers were secured, a far cry from the almost 300,000 servers patched during the first month after the vulnerability was revealed.

The Heartbleed flaw was publicly disclosed in early April and allows attackers to extract information from the memory of servers that run OpenSSL 1.0.1 through 1.0.1f, if they support an SSL feature called "heartbeat." The extracted information can include user passwords and long-term server private keys that can be used to decrypt SSL traffic captured from servers.

The impressive patching rate was also reflected in the results of other tests. Immediately after the flaw was made public, Ivan Ristic, who runs a monthly scan of the Internet's top 155,000 SSL-enabled sites as part of the SSL Pulse project, estimated that up to 30 percent of those sites might be vulnerable. A month later the SSL Pulse data was showing that only 1,291 sites, or 0.8 percent of the total, were still vulnerable to Heartbleed, leading Ristic to describe the Heartbleed patching effort as "incredibly fast" in a recent email.

However, it doesn't seem there has been a lot of progress since early May.

"Last night, now slightly over two months after Heartbleed, we scanned again, and found 300k (309,197) still vulnerable," Graham said Saturday in a blog post. "This indicates people have stopped even trying to patch. "

Since the SSL Pulse scan results for June show only 1,044 sites vulnerable to Heartbleed, the almost 310,000 vulnerable servers found by Graham are likely hosting less popular sites not covered by the project. And if those servers haven't been patched until now, despite significant efforts to raise awareness about this vulnerability on the Internet, it's likely many of them will remain vulnerable for some time to come.

"Even a decade from now, though, I still expect to find thousands of systems, including critical ones, still vulnerable," Graham said.

The researcher plans to decrease the frequency of his scans in the future. The next scan will be performed in a month, then in six months and then yearly after that, he said.